Art of cracking hydrocarbons



Dec. 1s, 1934.

w. s. GuLLl-:TTE

ART OF CRACKING HYDROCARBONS Filed Dec. 16, 1929 Y mi I.....JJ

ATTORNEYS In general the cracking operation may be carried out as described in application Serial No. 198,621 mentioned above. As illustrated, however, the digesting drums there described may be omitted and the hot oil products from the heate ing conduits may be discharged directly into the scrubbing towers. The heating furnaces may be arranged and operated, in general, as 'described in this mentioned application. The scrubbing towers may be arranged and operated, for eX- ample, as described in an application led March 7, 1929, Serial No. 345,199, by E. C. Herthel. The refining towers and following fractionating towers may be arranged and operated, if used, asi

described in an application led February 29, 1928, Serial No. 257,958, by E. C. Herthel. Liqueed polymers and associated constituents, higher boiling than suitable as components of the desired product, condensed in the fractionating towers following the refining towers may be returned to the scrubbing towers as described in an application filed February 29, 1928, Serial N o. 257,945, by Arnold C. Vobach.

YIn carrying out the invention in the appara-l tus illustrated, the fractionating towers 4a and 4b are controlled to condense rtherein constituents of thesame general boilingrange to form corresponding relatively higher boiling condensates, andthe fractionatingtowers 5a and 5b are similarly controlled to condense therein constituents of the same general boiling range to form corresponding relatively lower 'boiling condensates. The condensates separated 'in the fractionating towers 4a and 4b are'combined and supplied, through connections 17a and 17h and connection 11, to the heating conduit 1b. 'Similarly, the condensates separated in the fractionating towers 5a and 5b are combined and supplied, through connections 18a'and 18h and connection to the heating conduit 1a. A part of these latter condensates vmay vbe discharged through vconnections 27a and 27h.' The heating furnaces 2a and 2b are controlled; advanta- V geously, so that the oil stream flowing through the heating conduit 1al is heated to a higher temperature therein thanl is the oil stream nowing through the heating conduit 1b. f

In the production of motor fuel gasoline, for example, the heating furnace 2b maybe controlled so that the hot oil products are discharged from the heating conduit'lb at a temperature in the'neighb'orhood of 1'100-1120" F. and the heating furnace 2a may be controlled so ythat the hot oil products are discharged' from the heating conduit V1a at' a temperature in thej neighborhood of '1140-1160" the'fractionating towers 4a. and 4b may be controlled so that the temperaure of the lvapors escaping'through lconnections a and 15b respectively approximates 425-,500 F. and the fractionating towers 5a" and 5b controlled so` that thetemperatureI of the vaapproximates 375-- pors escaping therefrom 450 F.

Fractionating towers 4a, 4b, 5a and 5b may be' controlled by means of either or bothof the groups of reflux condensers 19a, 19h, 20a and 2017,`

through which raw stock may be circulated as a cooling medium beingat the same time vpreheated, and reflux condensers 21a, 2lb, 22a. and 2217, through which some extraneous cooling medium such as Water ymay be circulated, or by means of the direct introduction ofy raw stock through connections 23a, 23h, 24a and 2417, or by means of such introduction of raw stock supplemented by the operation of one or more of the-groups -of vbeing vaporized in the scrubbing towers to be condensed in one or the other of the successive fractionating towers to be supplied therefrom to the connectedheating conduit 1a or 1b. Relatively higherboiling raw stock corresponding to the condensate separated in the fractionating towers 4a and 4b or raw stock including lower boiling constituents may be supplied to the fractionating towers 4a and 4b through connection 23. Raw stock corresponding'to the condensate separated in fractionating towers 5a and 5b may be supplied to these fractionating towers through connection 24.' The same raw stock vmay lbe supplied through both 'connections A23 and 24 where the raw stock so supplied doesnot include any substantial amount of constituents higher boiling than suitable to be supplied to the heating conduit 1a. 'o Thev lfractionating towers 5a and 5b are with advantage controlled so that the escaping vapors condense to form a distillate product of the desired boilingrange or, if the fractionating towers-'7a` and' 7b`afre used, of somewhat broader boiling rangeincluding a limited proportion vof higher boiling constituents.

Iclaim: f'

1. In the cracking of hydrocarbon oils, the improvement which comprises owing two separate streams of oil through two separate heating conduits and heatingo'eachf stream of oil to a high cracking temperature in the vapor phase therein,

heating conduits to scrubbingoperations for the separation of tar and discharging tar-therefrom,

' separately subjecting the vapors from the two scrubbing operations to successive rst and second fractionating operations, condensing a crackedV distillate from the' vapors escaping from the fractionatingl operations, supplying the con`` densate from the two rsty fractionatingoperations to one of ther two vheating conduits andA supplying the condensate from the two second fractionating operations to `the'other of the two heating conduits. f

2. In thevcracking of hydrocarbonfoils, the improvement which comprises ilowing two separate streams of conduits and heating the stream of oil in one of the heating conduits toa high cracking tem? perature in the vapor phase and the' stream of oil in the other 'of the 'heating conduits to a higher cracking temperature in the vapor phase, separately subjecting the hot oil products discharged from the two heating conduits to scrubbing operations for the separation of tar and discharging tar therefrom, separately lsubjecting the vapors' from the twoscrubbingoperations' to successive first and second fractionating op'- erations, condensing a cracked distillate rfrom the vapors escaping from erations, supplying the condensate from the two second fractionating *operationsv to the heating conduit inwhich the oil stream lis'heated tothe" 1 o separately subjecting the hot oil products discharged from the twoI oil through two separateheating' the fractionating op,v

higher temperature and supplying the condensate from the two first fractionating operations to the other of the two heating conduits.

3. In the cracking of hydrocarbon oils, the improvement which comprises fiowing two separate streams of oil through two separate heating conduits and heating the stream of oil in one of the heating conduits to a high cracking temperature in the vapor phase and the stream of oil in the other of the heating conduits to a higher cracking temperature in the vapor phase, separately subjecting the hot oil products discharged from each of the two heating conduits to a separate scrubbing operation for the separation of tar, separately supplying liquid oil to and discharging tar from each of the scrubbing operations, subjecting the vapors remaining after separation of the tar to first and second fractionating operations, condensing a cracked distillate from the vapors escaping from the fractionating operations, supplying the condensate from the second fractionating operations to the heating conduit in which the oil stream is heated to the higher temperature, and supplying the condensate from the first fractionating operations to the other of the two heating conduits.

WILLIS S. GULLETTE. 

